help button home button Endocrine Society JCEM JCEM Call for Nominations for EIC
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Journal of Clinical Endocrinology & Metabolism, doi:10.1210/jc.2006-2819
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
92/7/2827    most recent
Author Manuscript (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hrabovszky, E.
Right arrow Articles by Liposits, Z.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hrabovszky, E.
Right arrow Articles by Liposits, Z.
Related Collections
Right arrow Male Endocrinology
Right arrow Neuroendocrinology and Pituitary
The Journal of Clinical Endocrinology & Metabolism Vol. 92, No. 7 2827-2830
Copyright © 2007 by The Endocrine Society

BRIEF REPORT

Gonadotropin-Releasing Hormone Neurons Express Estrogen Receptor-ß

E. Hrabovszky1, I. Kalló1, N. Szlávik, É. Keller, I. Merchenthaler and Z. Liposits

Laboratory of Endocrine Neurobiology (E.H., I.K., Z.L.), Institute of Experimental Medicine, Hungarian Academy of Sciences; Department of Forensic Medicine (N.S., E.K.), Semmelweis University; and Department of Neuroscience (Z.L.), Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, 1083 Hungary; and Departments of Epidemiology and Preventive Medicine and Anatomy and Neurobiology (I.M.), University of Maryland, Baltimore, Maryland 21201

Address all correspondence and requests for reprints to: Erik Hrabovszky, M.D., Ph.D., Department of Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083 Hungary. E-mail: hrabovszky{at}koki.hu.


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Context: Recent identification of the second estrogen receptor (ER) isoform (ER-ß) within GnRH neurons of the rodent brain has generated much enthusiasm in the field of neuroendocrine research by questioning the dogma that GnRH cells do not directly sense changes in circulating estrogens.

Objective: To address the issue of whether GnRH neurons of the human hypothalamus also contain ER-ß, we have performed dual-label immunocytochemical studies.

Design: Tissue sections were prepared from autopsy samples of male human individuals (n = 8; age < 50 yr), with sudden causes of death. Technical efforts were made to minimize postmortem interval (<24 h), optimize tissue fixation (use of a mixture of 2% paraformaldehyde and 4% acrolein for four tissue samples), and sensitize the immunocytochemical detection of ER-ß (application of silver-intensified nickel-diaminobenzidine chromogen).

Main Outcome Measure: Distribution and percent ratio of GnRH neurons that also contained ER-ß immunoreactivity were analyzed under the light microscope.

Results: With acrolein in tissue fixative, nuclear ER-ß immunoreactivity was observed in 10.8–28.0% of GnRH neurons of the four different individuals. ER-ß-containing GnRH neurons were widely distributed in the hypothalamus, without showing a noticeable preference in regional location.

Conclusions: The demonstration of ER-ß and the previous lack of detection of ER-{alpha} in human GnRH cells indicate that estrogens may exert direct actions upon GnRH neurons exclusively through ER-ß. In the light of differing ligand-binding characteristics of ER-ß from those of ER-{alpha}, this discovery offers a potential new approach to influence estrogen feedback to GnRH neurons through ER-ß-selective receptor ligands.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
THE GnRH (ALSO CALLED LHRH) neurosecretory system represents the final common hypothalamic pathway in the neuroendocrine control of reproduction. Changing levels of the ovarian sex steroid hormone 17ß-estradiol (E2) tightly regulate the activity of the neuroendocrine reproductive axis through feedback actions to GnRH cells (for review, see Ref. 1). In 1983, Shivers et al. (2) reported that GnRH neurons of the rat do not accumulate tritiated E2 in vivo. This surprising observation and the coherent results of subsequent immunocytochemical studies that failed to show any estrogen receptors (ERs) in GnRH neurons (3, 4) suggested that estrogen signaling is communicated to the GnRH neuronal system by estrogen-sensitive interneurons and/or glial cells. Shortly after the discovery of a second ER isoform (ER-ß), this view was challenged by reports of ER-{alpha} immunoreactivity (5), ER-{alpha} mRNA (6), ER-ß mRNA (6, 7), and [125I]estrogen-binding sites (7) in rodent GnRH neurons. In 2000, our group published the results of dual-label in situ hybridization experiments that showed absence of ER-{alpha} and presence of ER-ß mRNA hybridization signal in GnRH neurons of rats (7). This report was followed by the withdrawal (8) of previous ER-{alpha} mRNA detection in mouse GnRH neurons (6). The opinion that rodent GnRH neurons only contain the ER-ß isoform started to form. In 2001, two groups detected nuclear ER-ß immunoreactivity in 63–73% of GnRH neurons in the rat (9, 10). These immunocytochemical data, together with the previous observation that GnRH neurons of the rat are capable of accumulating a 125I-labeled estrogen compound in vivo (7), strengthened the concept that GnRH neurons synthesize functional ER-ß.

The recent demonstration of immunoreactive ER-ß in a large subset of ovine GnRH neurons (11) that lack ER-{alpha} (12) indicates that the selective presence of ER-ß in GnRH cells is not restricted to rodent species. The issue of whether or not GnRH neurons of the human also contain ER-ß remained unresolved. Therefore, in the present immunocytochemical study, we addressed the putative presence of ER-ß in GnRH neurons of the human hypothalamus.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Tissue samples

Human hypothalamic samples from eight male individuals with postmortem intervals between 12–14 h were obtained at autopsy from the Forensic Medicine Department of Semmelweis University (Budapest, Hungary) using protocols reviewed and approved by the Regional Committee of Science and Research Ethics (TUKEB 49/1999). Selection criteria included sudden causes of death, lack of history of neurological and endocrinological disorders, postmortem intervals between 12–24 h and age less than 50 yr. Hypothalamic blocks were dissected out according to guidelines of the optic chiasm (rostrally), mammillary bodies (caudally), the anterior commissure (dorsally), and 2 cm lateral from the midsagittal plane (laterally). The tissue blocks were initially rinsed for 5 min in several changes of 4% paraformaldehyde solution prepared with 0.1 M PBS (pH 7.4) and then transferred for 2 d into a freshly prepared mixture of 4% acrolein and 2% paraformaldehyde (4 C).

Section preparation

Tissue blocks were infiltrated with 30% sucrose for 5 d and cut in half in the midsagittal plane to reduce section size. The hemi-hypothalami were aligned in a freezing mold, surrounded with Jung tissue freezing medium (Leica Microsystems, Nussloch Gmbh, Germany; diluted 1:1 with 0.9% sodium chloride solution), frozen on powdered dry ice, and sectioned serially at 30 µm with a Leica CM 3050 S cryostat (Leica) according to the plane of the lamina terminalis. The sections were stored in antifreeze solution (30% ethylene glycol, 25% glycerol, 0.05 M phosphate buffer) at –20 C until used.

Dual-label immunocytochemical studies

Every 20th section from each block was processed for dual-label immunocytochemistry. Sections were pretreated with 1% sodium borohydride (30 min), a mixture of 0.5% H2O2 and Triton X-100 (30 min), 3.7% paraformaldehyde in 30% ethanol (30 min), 8% thioglycolic acid (30 min), and 2% normal horse serum (30 min). The sections were first incubated in a 1:20,000 dilution (in 2% normal horse serum) of primary ER-ß antibodies (P3; gift from Dr. P. T. Saunders, Edinburgh, UK) raised in sheep and targeting the A/B region of human ER-ß (13), followed by biotinylated secondary antibodies (Jackson ImmunoResearch Europe Ltd., Soham, Cambridgeshire, UK; 1:1,000) and ABC Elite reagent (60 min each). The signal was visualized with nickel-intensified diaminobenzidine and then post-intensified with silver-gold (9, 10). Subsequently, GnRH immunoreactivity was detected with rabbit primary antibodies (LR-1, 1:20,000; gift from Dr. R. A. Benoit, Montreal, Canada) using the biotinylated secondary antibody-ABC technique and nonintensified diaminobenzidine as chromogen. The dual-labeled sections were mounted on microscope slides and coverslipped with DPX mounting medium (Fluka Chemie, Buchs, Switzerland).


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Distribution of ER-ß immunoreactivity in the human hypothalamus

The immunocytochemical detection of ER-ß caused nuclear immunolabeling in hypothalamic (Fig. 1AGo) neurons. The silver-gold intensification step enhanced the staining of labeled nuclei and rendered the nickel-diaminobenzidine chromogen dark and granular (Figs. 1AGo and 2Go, A–G). No immunoreactivity was observed if the primary or secondary antibodies were omitted or when the ER-ß antibody had been immunoneutralized with 5 µg/ml of the immunization antigen (Fig. 1BGo). Increasing dilutions of the primary antibody led to a commensurate attenuation of the immunoreactive signal.


Figure 1
View larger version (49K):
[in this window]
[in a new window]

  		FIG. 1. Detection of ER-ß-immunoreactive neurons in the human hypothalamus. The ER-ß antigen was visualized with the P3 antibodies using the silver-gold intensification of the nickel-diaminobenzidine peroxidase reaction product (black). A, Immunolabeling was localized to the cell nuclei, was abundant in the dorsolateral (SODL) and ventromedial subdivisions (SOVM) of the supraoptic nucleus, but also occurred in high numbers in other hypothalamic regions, including the lateral hypothalamic area (LHA). Note that after the immunolocalization of ER-ß, this section also went through the immunocytochemical detection of GnRH using diaminobenzidine chromogen. The two GnRH neurons in boxed regions exhibited ER-ß labeling in their cell nucleus, as shown at high magnification in Fig. 2Go, A and B. B, Section showing the lack of any ER-ß signal went through the immunocytochemical detection of ER-ß using a primary antiserum preabsorbed with 5 µg/ml of the immunization antigen. Scale bar, 100 µm.

 

Figure 2
View larger version (103K):
[in this window]
[in a new window]

  		FIG. 2. Demonstration of ER-ß immunoreactivity in GnRH neurons of the human hypothalamus. The ER-ß antigen was detected using the silver-gold intensification of nickel-diaminobenzidine peroxidase reaction product (black), whereas GnRH neurons were stained with the nonintensified diaminobenzidine chromogen (brown). Cell nuclei immunoreactive for ER-ß occurred in high numbers in the lateral hypothalamic area (LHA) (A and B), ventromedial nucleus (VMH) (C and D), medial basal hypothalamus (MBH) (C and E), infundibular nucleus (INF) (F), and lateral tuberal nucleus (LTU) (F and G). The GnRH neurons were scattered within the same regions and often contained ER-ß-immunoreactive nucleus. Note two dual-labeled GnRH neurons in the LHA (A and B; also shown in boxed regions of Fig. 1AGo) that are bipolar in shape. Inset in B demonstrates the characteristic nuclear labeling for ER-ß. Single-labeled (E) and double-labeled (D and G) GnRH neurons are both found in the MBH (D) and the LTU (G), marked with boxes in low-power images C and F. Some GnRH cells exhibit a multipolar morphology (E and G). Scale bars, 100 µm (C and F), 25 µm (A, B, D, E, and G), and 5 µm (high-power inset in B).

 
The nuclear ER-ß signal occurred in common in the hypothalamic sections of the eight individuals. However, the staining intensity varied largely among the brains, suggesting differences in antigen preservation and/or receptor abundance. Clearly, the labeling was heaviest in tissues fixed with the acrolein/paraformaldehyde mixture. ER-ß-immunoreactive cell nuclei were widely distributed in the hypothalamus, including the supraoptic nucleus (Fig. 1AGo) where previous studies have shown its presence in magnocellular oxytocin and vasopressin neurons (14). Considerable variations were noticed in labeling intensity of individual ER-ß-containing cell nuclei (Fig. 1AGo).

Identification of ER-ß-immunoreactive GnRH neurons

GnRH neurons occurred in very low numbers within individual hypothalamic sections (Figs. 1AGo and 2CGo). Bipolar (Fig. 2BGo) and multipolar (Fig. 2GGo) neuronal shapes were distinguishable. High-power microscopic analysis of acrolein/paraformaldehyde-fixed sections revealed ER-ß in a subset of GnRH neurons (Fig. 2Go, B, D, and G), whereas other GnRH cells contained no signal for ER-ß (Fig. 2EGo). Dual-labeled neurons occurred in highest numbers in the lateral and dorsal hypothalamic areas, in the infundibular, lateral tuberal, ventromedial, periventricular, supraoptic, and paraventricular nuclei, without showing a preferential location in any particular hypothalamic region (Fig 2Go). Their percent ratio in the four individuals was 10.8, 11.1, 21.7, and 28.0%, respectively. Paraformaldehyde fixation, in itself, was not sufficient to visualize any ER-ß immunoreactivity in GnRH neurons.


   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Results of this dual-label immunocytochemical study provide the first evidence for ER-ß in human GnRH neurons. This observation, together with the previously reported lack of ER-{alpha} in these cells (15) indicate that E2 may directly regulate human GnRH neurons via the ER-ß receptor isoform.

The use of postmortem tissue samples in this study raises the question as to what extent suboptimal tissue processing compromised the sensitivity of ER-ß detection. Paraformaldehyde fixation, in itself, was clearly incompatible with the visualization of any ER-ß immunoreactivity in the cell nuclei of GnRH cells. Similarly to this observation on human samples, the inclusion of acrolein in the fixative was critically important to maximize the number of ER-ß-immunoreactive GnRH neurons in the rat (9, 10). On the other hand, paraformaldehyde-based fixation of human hypothalamic tissue samples clearly ensured sufficient antigen preservation to visualize ER-ß immunoreactivity in magnocellular neurosecretory neurons (14). The uncontrolled tissue damage before tissue fixation could interfere further with the visualization of ER-ß in GnRH cells of postmortem human tissues. This could account for the variations in the intensity of ER-ß staining and in the percentage (10.8–28.0%) of the ER-ß-immunoreactive GnRH neurons across the four acrolein/paraformaldehyde-fixed samples. These technical considerations suggest that the ratio of ER-ß-expressing GnRH neurons could be significantly underestimated in this study.

A physiological correlate of our present studies is the use of male hypothalami. This has eliminated differences in the ER-ß staining of GnRH neurons as an effect of variations in circulating estrogen levels. It is worth noting that our previous immunocytochemical study on rats, indeed, revealed a negative impact of E2 on the percent ratio of ER-ß-immunoreactive GnRH neurons (10). Given that only male individuals were included in this study, the potential sexual dimorphism of the colocalization phenomenon will also require future clarification with the parallel use of similarly processed tissue samples from men and women. In this context, it is worth mentioning that previous in situ hybridization (9) and immunocytochemical (9) studies failed to detect any significant gender difference in the percent ratio of ER-ß-synthesizing GnRH neurons in rats. Although results of preliminary studies also indicate the presence of ER-ß in GnRH neurons of the human female, the low sample number has not allowed yet a systematic assessment of potential sex differences (Hrabovszky, E., unpublished observations).

The results of the present immunocytochemical experiments provide strong evidence for the presence of ER-ß in human GnRH neurons. In the light of previous studies that showed the lack of ER-{alpha} mRNA in human GnRH neurons (15) and the accumulating evidence that only the ER-ß isoform occurs in GnRH neurons of rodents (7, 8) and ewes (11), it is reasonable to speculate that direct estrogen actions upon human GnRH neurons may be exerted exclusively via ER-ß. With this information, the growing number of ER-ß-selective ligands may offer a unique tool to modulate GnRH cell functions and thereby the human reproductive axis. This long-term perspective necessitates a solid knowledge about the direct actions of ER-ß on GnRH cell functions. Several studies on rodent GnRH neurons have already identified such ER-ß-mediated direct estrogen actions. The fast, nongenomic actions of ligand-bound ER-ß include rapid phosphorylation of cAMP-response element-binding protein (16) and stimulation of intracellular calcium oscillations (17) in mouse GnRH neurons. Estrogen also increases excitability of mouse GnRH neurons, partly via mechanisms that include phosphorylation of potassium channels (18). In vitro transfection experiments have also established the role of ER-ß in a ligand-independent transcriptional activation and a ligand-dependent transcriptional repression of the mouse GnRH promoter (19). Furthermore, in vivo studies with newly available ER-ß-selective agonist ligands provided evidence for the ER-ß-mediated induction of galanin mRNA expression in GnRH neurons of rats (20). Although the precise role of ER-ß in fertility of laboratory animals and humans remains to be determined, one has to remain aware of well-established indirect estrogen actions that involve interneurons expressing the ER-{alpha} isoform.

In summary, we have identified ER-ß immunoreactivity in GnRH neurons of the human hypothalamus. Because these cells lacked ER-{alpha} in previous studies, the new findings indicate that estrogens may exert direct actions upon GnRH cells selectively through the ER-ß isoform. The differing ligand-binding characteristics of ER-ß from those of the classical ER-{alpha} offers a potential new strategy to influence estrogen feedback mechanisms to human GnRH neurons via recently available ER-ß-selective ligands.


   Acknowledgments
 
We thank Drs. R. A. Benoit and P. T. Saunders for kindly providing the LR1 (GnRH) and P3 (ER-ß) antibodies, respectively, and E. Dobó for helpful technical advice.


   Footnotes
 
This work was supported by grants from the National Science Foundation of Hungary (OTKA T43407 and T46574), NKFP 1A/002/2004, and the European Union FP6 funding (LSHM-CT-2003-50304).

This publication reflects the authors’ views and not necessarily those of the European Union. The information in this document is provided as is, and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information at its sole risk and liability.

Disclosure: All of the authors have nothing to declare.

First Published Online April 24, 2007

1 E.H. and I.K. have contributed equally to the studies presented in this manuscript. Back

Abbreviations: E2, 17ß-Estradiol; ER, estrogen receptor.

Received December 20, 2006.

Accepted April 16, 2007.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Petersen SL, Ottem EN, Carpenter CD 2003 Direct and indirect regulation of gonadotropin-releasing hormone neurons by estradiol. Biol Reprod 69:1771–1778[Abstract/Free Full Text]
  2. Shivers BD, Harlan RE, Morrell JI, Pfaff DW 1983 Absence of oestradiol concentration in cell nuclei of LHRH-immunoreactive neurones. Nature 304:345–347[CrossRef][Medline]
  3. Watson R, Langub M, Landis J1992 Further evidence that most luteinizing hormone-releasing hormone neurons are not directly estrogen-responsive: simultaneous localization of luteinizing hormone-releasing hormone and estrogen receptor immunoreactivity in the guinea pig brain. J Neuroendocrinol 4:311–318
  4. Herbison AE, Theodosis DT 1992 Localization of oestrogen receptors in preoptic neurons containing neurotensin but not tyrosine hydroxylase, cholecystokinin or luteinizing hormone-releasing hormone in the male and female rat. Neuroscience 50:283–298[CrossRef][Medline]
  5. Butler JA, Sjoberg M, Coen CW 1999 Evidence for oestrogen receptor {alpha}-immunoreactivity in gonadotrophin-releasing hormone-expressing neurones. J Neuroendocrinol 11:331–335[CrossRef][Medline]
  6. Skynner MJ, Sim JA, Herbison AE 1999 Detection of estrogen receptor {alpha} and ß messenger ribonucleic acids in adult gonadotropin-releasing hormone neurons. Endocrinology 140:5195–5201[Abstract/Free Full Text]
  7. Hrabovszky E, Shughrue PJ, Merchenthaler I, Hajszan T, Liposits Z, Carpenter CD, Petersen SL 2000 Detection of estrogen receptor-ß messenger ribonucleic acid and 125I-estrogen binding sites in luteinizing hormone-releasing hormone neurons of the rat brain. Endocrinology 141:3506–3509[Abstract/Free Full Text]
  8. Herbison A, Skynner M, Sim J 2001 Lack of detection of estrogen receptor-{alpha} transcripts in mouse gonadotropin-releasing hormone neurons. Endocrinology 142:492
  9. Hrabovszky E, Steinhauser A, Barabás K, Shughrue PJ, Petersen SL, Merchenthaler I, Liposits Z 2001 Estrogen receptor-ß immunoreactivity in luteinizing hormone-releasing hormone neurons of the rat brain. Endocrinology 142:3261–3264[Abstract/Free Full Text]
  10. Kallo I, Butler JA, Barkovics-Kallo M, Goubillon ML, Coen CW 2001 Oestrogen receptor ß-immunoreactivity in gonadotropin releasing hormone-expressing neurones: regulation by oestrogen. J Neuroendocrinol 13:741–748[CrossRef][Medline]
  11. Skinner DC, Dufourny L 2005 Oestrogen receptor ß-immunoreactive neurones in the ovine hypothalamus: distribution and colocalisation with gonadotropin-releasing hormone. J Neuroendocrinol 17:29–39[CrossRef][Medline]
  12. Herbison AE, Robinson JE, Skinner DC 1993 Distribution of estrogen receptor-immunoreactive cells in the preoptic area of the ewe: co-localization with glutamic acid decarboxylase but not luteinizing hormone-releasing hormone. Neuroendocrinology 57:751–759[Medline]
  13. Saunders PT, Millar MR, Williams K, Macpherson S, Harkiss D, Anderson RA, Orr B, Groome NP, Scobie G, Fraser HM 2000 Differential expression of estrogen receptor-{alpha} and -ß and androgen receptor in the ovaries of marmosets and humans. Biol Reprod 63:1098–1105[Abstract/Free Full Text]
  14. Hrabovszky E, Kallo I, Steinhauser A, Merchenthaler I, Coen CW, Petersen SL, Liposits Z 2004 Estrogen receptor-ß in oxytocin and vasopressin neurons of the rat and human hypothalamus: immunocytochemical and in situ hybridization studies. J Comp Neurol 473:315–333[CrossRef][Medline]
  15. Rance NE, McMullen NT, Smialek JE, Price DL, Young 3rd WS 1990 Postmenopausal hypertrophy of neurons expressing the estrogen receptor gene in the human hypothalamus. J Clin Endocrinol Metab 71:79–85[Abstract]
  16. Abraham IM, Han SK, Todman MG, Korach KS, Herbison AE 2003 Estrogen receptor ß mediates rapid estrogen actions on gonadotropin-releasing hormone neurons in vivo. J Neurosci 23:5771–5777[Abstract/Free Full Text]
  17. Temple JL, Laing E, Sunder A, Wray S 2004 Direct action of estradiol on gonadotropin-releasing hormone-1 neuronal activity via a transcription-dependent mechanism. J Neurosci 24:6326–6333[Abstract/Free Full Text]
  18. DeFazio RA, Moenter SM 2002 Estradiol feedback alters potassium currents and firing properties of gonadotropin-releasing hormone neurons. Mol Endocrinol 16:2255–2265[Abstract/Free Full Text]
  19. Pak TR, Chung WC, Roberts JL, Handa RJ 2006 Ligand-independent effects of estrogen receptor ß on mouse gonadotropin-releasing hormone promoter activity. Endocrinology 147:1924–1931[Abstract/Free Full Text]
  20. Merchenthaler I, Hoffman GE, Lane MV 2005 Estrogen and estrogen receptor-ß (ERß)-selective ligands induce galanin expression within gonadotropin hormone-releasing hormone-immunoreactive neurons in the female rat brain. Endocrinology 146:2760–2765[Abstract/Free Full Text]




This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
92/7/2827    most recent
Author Manuscript (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hrabovszky, E.
Right arrow Articles by Liposits, Z.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hrabovszky, E.
Right arrow Articles by Liposits, Z.
Related Collections
Right arrow Male Endocrinology
Right arrow Neuroendocrinology and Pituitary

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals